I simply cannot get Sparkle to work

The exact procedure for importing the framework is documented here: http://sparkle.andymatuschak.org/documentation/pmwiki.php/Documentation/BasicSetup

Please check your console for debug output and, if nothing's there, please post your appcast here.

Hehe. I didn't even know about the console feature in Xcode. I just started using it a week ago ^-^

This is what I get when I click Check for Updates:

2009-04-15 10:57:16.227 Pow![1301:10b] You must specify the URL of the appcast as the SUFeedURLKey in either the Info.plist or the user defaults!

I did create the SUFeedURL item in the info plist and pointed it to the right address though.

This is my appcast xml entry:

<item>
 <title>Version 1.1.0</title>
   <sparkle:releaseNotesLink>
     http://www.steisen.com/pow/1.1.0.html
   </sparkle:releaseNotesLink>
 <pubDate>Wed, 15 Apr 2009 10:56:21 -0700</pubDate>
 <enclosure
  url="http://www.steisen.com/pow/pow_1.1.0.zip"
  sparkle:version="1.1.0"
  type="application/octet-stream"
  length="1749832"
  sparkle:dsaSignature="blah blah blah my public signature is usually here"
 />
</item>

Okay, sounds like an Info.plist problem. Please paste the contents of yours here.

{
 "CFBundleDevelopmentRegion" = English;
 CFBundleExecutable = "${EXECUTABLE_NAME}";
 CFBundleIconFile = Pow;
 CFBundleIdentifier = "com.steisen.pow";
 "CFBundleInfoDictionaryVersion" = "6.0";
 CFBundleName = "${PRODUCT_NAME}";
 CFBundlePackageType = APPL;
 "CFBundleShortVersionString" = "1.1.0";
 CFBundleSignature = "????";
 CFBundleVersion = "1.1.0";
 NSAppleScriptEnabled = YES;
 NSMainNibFile = MainMenu;
 NSPrincipalClass = NSApplication;
 SUFeedUrl = "http://www.steisen.com/pow/updates.xml";
 SUPublicDSAKeyFile = "dsa_pub.pem";
}

Info.plist keys are case sensitive; it's "SUFeedURL", not "SUFeedUrl."

Awesome! Thank you so much. One more quick question if you don't mind. I tested your solution quickly with the most recent revision (1.1.0) which is what currently posted in my appcast. When I checked for updates it gave me an update error. Is that normal behavior when the versions match, or should it tell me that I'm up to date?

It should tell you that it's up to date, so that's indicative of some other problem. But as before, more information is logged to the console. Hopefully that'll be enough for you to fix it.

Thanks again, Andy :)